The fingers (more specifically, finger tips) of a robot hand are generally formed of a single material having an appropriate coefficient of friction (e.g., silicone rubber). In contrast, the below-mentioned Non-patent Ref. No. 1 teaches formation of a finger tip from a skeletal frame and a nail made of aluminum, and skin made of soft sponge that covers the skeletal frame. Further, as set out in Patent Ref. No. 1, rigid inner skin is provided to cover a tactile sensor attached to a base portion serving as a skeletal frame and flexible outer skin is provided to cover the inner skin.
Non-patent Ref. No. 1: Paper at the 16th Annual Conference of the Robotics Society of Japan, “Development of finger-tip of its structural design aimed at adjustment of contact area,” Robotic Society of Japan, September 1998, pp 1437-1438.
Patent Ref. No. 1: Japanese Patent Publication Hei 7(1995)-8477